This invention relates to the selection and use of environmentally preferred fluids and fluid blends which exhibit low or reduced reactivity with respect to ozone formation. These environmentally preferred fluids and fluid blends are useful in a number of applications, particularly as industrial solvents, and allow formulators an effective means to improve the environmental performance of their formulations or products.
Fluid applications are broad, varied, and complex, and each application has its own set of characteristics and requirements. Proper fluid selection and fluid blend development have a large impact on the success of the operation in which the fluid is used. For instance, in a typical industrial coatings operation, a blend of several fluids is used in order to get an appropriate evaporation profile. Such a blend must also provide the appropriate solvency properties, including formulation stability, viscosity, flow/leveling, and the like. The fluid blend choice also affects the properties of the dry film, such as gloss, adhesion, and the like. Moreover, these and other properties may further vary according to the application method (e.g., spray-on), whether the substrate is original equipment (OEM), refinished, etc., and the nature of the substrate coated.
Other operations involving the use of fluids and fluid blends include cleaning, printing, delivery of agricultural insecticides and pesticides, extraction processes, use in adhesives, sealants, cosmetics, and drilling muds, and countless others. The term xe2x80x9cfluidxe2x80x9d encompasses the traditional notion of a solvent, but the latter term no longer adequately describes the possible function of a fluid or blend in the countless possible operations. As used herein the term xe2x80x9cfluidxe2x80x9d includes material that may function as one or more of a carrier, a diluent, a surface tension modifier, dispersant, and the like, as well as a material functioning as a solvent, in the traditional sense of a liquid which solvates a substance (e.g., a solute).
The term xe2x80x9cindustrial solventxe2x80x9d applies to a class of liquid organic compounds used on a large scale to perform one or more of the numerous functions of a fluid in a variety of industries. Relatively few of the large number of known organic compounds that could be used as fluids find use as industrial solvents. Fluids that are used in large quantities have heretofore been selected because they can be produced economically and have attractive safety and use characteristics in manufacturing, consumer and commercial environments. Examples of commercial solvents and their uses as industrial solvents are described in an article entitled xe2x80x9cSolvents, Industrialxe2x80x9d, by Don A. Sullivan, Shell Chemical, Encyclopedia of Chemical Technology, 4th. ed., V. 22, pp. 529-571 (III) (1997).
In addition to the problems with fluid and fluid blend selection mentioned at the outset, there is also the problem that, in most applications, at least some of the fluid evaporates and can escape into the environment. Although many industrial coating operations, such as in original equipment manufacturing (OEM), utilize control equipment to capture or incinerate  greater than 95% of the solvent emissions, nevertheless in a majority of applications some of the solvents inevitably enters the atmosphere.
The United States Environmental Protection Agency (EPA) has developed National Ambient Air Quality Standards (NAAQS) for six pollutants: ozone, nitrogen oxides (NOx), lead, carbon monoxide, sulfur dioxide and particulates. Of all the NAAQS standards, ozone non-attainment has the greatest impact on solvent operations.
Solvents typically are volatile organic compounds (VOC), which are involved in complex photochemical atmospheric reactions, along with oxygen and nitrogen oxides (NOx) in the atmosphere under the influence of sunlight, to produce ozone. Ozone formation is a problem in the troposphere (low atmospheric or xe2x80x9cground-basedxe2x80x9d), particularly in an urban environment, since it leads to the phenomenon of smog. Since VOC emissions are a source of ozone formation, industrial operations and plants using solvents are heavily regulated to attain ozone compliance. As different regulations have been adopted, the various approaches to controlling pollution have evolved. Certain early regulations controlled solvent composition, while later regulations primarily concerned overall VOC reduction.
According to current VOC emission regulations in the U.S.A., solvents generally belong to one of two groups depending on their reactivity toward atmospheric photochemical ozone formation: (a) Negligible reactivity organic compounds which generate about the same or less quantity of ozone as would be produced by the same weight % as ethane. These organic compounds are exempt from the definition of a VOC and are not considered to be a VOC in any solvent (fluid) composition. There are numerous such compounds exempted by the EPA from the definition of VOC. However, a majority of such exempted compounds are halogenated derivatives which can possess one or more of the following deficiencies: toxicity, ozone depletion, or waste disposal or incineration problems. Other non-halogenated, oxygenated organic compounds, such as acetone and methyl acetate, have been exempted by the EPA, but such compounds have extremely high evaporation rates and high flammability so as to reduce their applicability in numerous applications. Other such organic compounds, such as tertiary butyl acetate which is under exemption consideration by the EPA, while having a significantly improved flammability level and evaporation rate, may be too chemically and thermally unstable for many applications. (b) All other oxygenated and hydrocarbon solvents are considered to be VOC""s and treated by the EPA as equally (on a weight basis) polluting. A more recent U.S. regulation has combined VOC reduction with composition constraints. While the traditional source of emission reduction is large stationary industrial facilities, the EPA and other governmental entities have turned increasingly to consumer and commercial products for reduction in their solvent usage as an additional means to lower VOC emission and therefore ozone formation. Numerous government and trade publications discuss VOC""s, and information is readily available on the Internet. See, for instance, http://www.paintcoatings.net/VOCW97.html.
Various measurements of reactivity with respect to ozone formation are known. For instance, reactivity can be measured in environmental smog chambers, or they may be calculated using computer airshed models. See, for instance, Dr. William P. L. Carter, xe2x80x9cUncertainties and Research Needs in Quantifying VOC Reactivity for Stationary Source Emission Controlsxe2x80x9d, presented at the California Air Resources Board (CARB) Consumer Products Reactivity Subgroup Meeting, Sacramento, Calif. (Oct. 17, 1995).
There has also been developed a xe2x80x9cKOH scalexe2x80x9d, which provides a relative scale of the reactivity of VOC with the OH radicals involved in the complex reactions that produce ozone. See, for instance, Picquet et al., Int. J. Chem. Kinet. 30, 839-847 (1998); Bilde et al., J. Phys. Chem. A 101, 3514-3525 (1997).
Numerous other reactivity scales are known and new reactivity scales are constantly being developed. Since this is a rapidly changing area of research, the most up-to-date information is often obtained via the Internet. One example is Airsite, the Atmospheric Chemistry International Research Site for Information and Technology Exchange, sponsored by the University of North Carolina and the University of Leeds, at http://airsite.unc.edu.
Another way to measure the reactivity of a chemical in ozone formation is by using a technique developed by Dr. Carter (supra) at the Center for Environmental Research and Technology (CERT), University of California at Riverside. The CERT technique measures xe2x80x9cincremental reactivitiesxe2x80x9d, the incremental amount of ozone that is produced when the chemical is added to an already polluted atmosphere.
Two experiments are conducted to measure the incremental reactivity. A base case experiment measures the ozone produced in an environmental smog chamber under atmospheric conditions designed to represent a polluted atmosphere. The second experiment called xe2x80x9cthe test casexe2x80x9d adds the chemical to the xe2x80x9cpollutedxe2x80x9d smog chamber to determine how much more ozone is produced by the newly added chemical. The results of these tests under certain conditions of VOC and nitrogen oxide ratios are then used in mechanistic models to determine the Maximum Incremental Reactivities (MIR), which is a measure of ozone formation by the chemical compound in question.
The State of California has adopted a reactivity program for alternative fuels based on this technique and the EPA has exempted several compounds due to studies conducted by CERT. See, for instance, Federal Register 31,633 (Jun. 16, 1995) (acetone); 59 Federal Register 50,693 (Oct. 5, 1994) (methyl siloxanes), Federal Register 17,331 (Apr. 9, 1998) (methyl acetate). CARB and EPA have uses a weight average MIR for regulatory purposes, wherein the weight average MIR of a solvent blend is calculated by summing the product of the weight percent of each solvent and its respective MIR value.
A list of compounds and their MIR values is available in the Preliminary Report to California Air Resources Board, Contract No. 95-308, William P. L. Carter, Aug. 6,1998. A table of known MIR values may be found on the internet at http://helium.ucr.edu/xcx9ccarter/index.html. CERT obtains other incremental reactivities by varying the ratios of VOC and nitrogen oxides. A detailed explanation of the methods employed and the determination of incremental reactivities and MIR scale may be found in the literature. See, for instance, International Journal of Chemical Kinetics, 28, 497-530 (1996); Atmospheric Environment, 29, 2513-2527 (1995), and 29, 2499-2511 (1995); and Journal of the Air and Waste Management Association, 44, 881-899 (1994); Environ. Sci. Technol. 23, 864 (1989). Moreover, various computer programs to assist in calculating MIR values are available, such as the SAPRC97 model, at http://helium.ucr.edu/xcx9ccarter/saprc97. htm.
Any of these aforementioned scales could be used for regulatory purposes, however the MIR scale has been found to correlate best to peak ozone formation in certain urban areas having high pollution, such as the Los Angeles basin. MIR values can be reported as the absolute MIR determined by the CERT method or as a relative MIR. One common relative MIR scale uses the Reactive Organic Gas (ROG) in the base case as a benchmark. The Absolute Reactivity ROG is 3.93 g O3 per gram ROG. This value is then the divisor for the absolute MIR of other VOCs, if MIR is cited relative to ROG. Absolute reactivities related to the ROG with the above mentioned absolute reactivity 3.93 are provided in xe2x80x9cUpdated Maximum Incremental Reactivity Scale for Regulatory Applicationsxe2x80x9d, Preliminary Report to California Air Resources Board, Contract No. 95-308, William P. Carter, Aug. 6, 1998. For the purposes of this invention and specification, unless otherwise specifically stated, all MIR values provided herein are Absolute MIR values. It is understood, however, that the Absolute MIR values can be converted to Relative MIR and back to Absolute MIR by division or multiplication of MIR by ROG.
Current regulations based on VOC emissions do not take into consideration the wide difference in ozone formation among non-exempt VOC compounds. For example, two non-exempt VOC compounds can have dramatically different ozone formation characteristics. Accordingly, current regulations do not encourage end users to minimize ozone formation by using low reactivity solvent compositions. Although there are federal and state regulatory trends toward requiring the reduction of the reactivity of solvents, the number of exempt solvents is small and in no way satisfies all the other properties required for an effective solvent such as good solvency, appropriate flash point, evaporation rate, boiling temperature, chemical and thermal stability.
Solvents currently viewed as essentially non-ozone producing are those which have reactivity rates in the range of ethane. Ethane has a measured reactivity based on the MIR method of 0.35. In fact, the EPA has granted a VOC exemption to certain solvents with reactivity values in this range including-acetone (MIR=0.48) and methyl acetate (MIR=0.12).
However, the number of known materials having reactivities of 0.50 or less based on the MIR scale is relatively small. Moreover, it is a discovery of the present inventors that many if not most of the known fluids having acceptable reactivities with respect to ozone formation have other unfavorable performance characteristics, e.g., poor solvent properties, low flash point, inappropriate evaporation rate or volatility characteristics, unacceptable toxicity, unacceptable particulate matter formation, thermal or chemical instability and as such have limited, if any, applicability in industry. For example, ethane is a gas under ambient conditions and hence is a poor choice as an industrial solvent. Methyl acetate has an excellent MIR=0.12, but a low flash point of about xe2x88x9212xc2x0 C.; acetone has an acceptable MIR=0.48, but is extremely flammable. As a further example, tertiary butyl acetate (t-butyl acetate) has an excellent MIR=0.21, but has limited thermal stability and is unstable to acid catalysts which may be present in an industrial operation.
Regarding particulate matter, the EPA has recently proposed standards for particulate matter under 2.5 xcexcm (microns) in diameter (xe2x80x9cPM2.5xe2x80x9d). See 61 Federal Register 65638-65713 (Dec. 13, 1996). The proposal sets an annual limit, spatially averaged across designated air quality monitors, of 15 xcexcg/m3, and a 24-hour standard of 65 xcexcg/m3. Numerous discussions of this proposed standard are available on the internet, such as at http://www.cnie.org/nle/airxcx9chtml, which cites numerous references (such as Wolf, xe2x80x9cThe Scientific Basis for a Particulate Matter Standardxe2x80x9d, Environmental Management (October, 26-31, 1996)). As far as the present inventors are aware, the prior art has not addressed ways of meeting these proposed requirements, much less in meeting these requirements in conjunction with ozone reduction requirements.
Moreover, the present inventors have also discovered that in many applications, VOC exempt solvents cannot be used as a one-for-one replacement for conventional solvents. Rather the formulator must balance a number of performance factors to develop an acceptable solvent or solvent blend for a particular application. Some factors are more relevant than others for specific applications. Nevertheless, many performance factors are similar for a number of applications.
Numerous attempts have been made to utilize the concept of xe2x80x9cenvironmentally friendlyxe2x80x9d fluids in practical applications. For instance, there are a number of cleaning and/or stripping formulations available that are said to overcome certain prior art environmental problems. Examples include a binary azeotrope of octamethyltrisiloxane with n-propoxypropanol (U.S. Pat. No. 5,516,450), hexamethyldisiloxane and azeotropes and other mixtures thereof (U.S. Pat. No. 5,773,403), a nonazeotropic mixture including a halocarbon and an oxygenated organic solvent component having at least 3 carbons, which may be, for instance, dimethylcarbonate (U.S. Pat. No. 5,552,080), and a composition comprising an amide and a dialkyl carbonate (U.S. Pat. No. 4,680,133).
In addition, there have been a number of patents and literature references to materials intended to replace chlorofluorocarbons (CFCs) as, for instance, blowing agents. These efforts address stratospheric ozone depletion, which is the opposite phenomenon addressed by the present invention. Examples include the use of dimethoxymethane and cyclopentane (U.S. Pat. Nos. 5,631,305; 5,665,788; and 5,723,509), cyclopentane (U.S. Pat. No. 5,578,652) and polyglycols (U.S. Pat. No. 5,698,144). Still further, a xe2x80x9cnon-ozone depletingxe2x80x9d solvent comprising halogenated compounds and an aliphatic or aromatic hydrocarbon compound having 6-20 carbon atoms is disclosed in U.S. Pat. No. 5,749,956. Similarly, U.S. Pat. No. 5,004,480 describes a method for reducing the levels of air pollution resulting from the combustion of diesel fuel in engines comprising blending dimethyl carbonate (DMC) with diesel fuel and combusting the blended fuel in engines. U.S. Pat. No. 5,032,144 also discusses the addition of oxygenates, including methyl pivalate (methyl 1,1,1-trimethyl acetate) to gasoline (as octane boosters). The problems addressed by these patents do not relate to the problem of industrial solvent evaporation.
WO 98/42774 discloses solvent-resin compositions which xe2x80x9cdo not contribute appreciably to the formation of ground based ozonexe2x80x9d. Organic solvents are selected based upon having xe2x80x9creaction rates with hydroxyl ion slower than ethanexe2x80x9d, and generally selected from halogenated solvents such as chlorobromomethane, methyl chloride, and the like. The only non-halogenated solvents that are suggested are n-alkanes (C12-C18), methyl and t-butyl acetate, acetone, dimethoxymethane, and mineral oils.
However, heretofore there has been no general solution to the problem of ground-based ozone formation that also provides for a fluid with appropriate performance attributes for an industrial solvent.
The present invention is directed to environmentally preferred fluids and fluid blends, their use as industrial solvents, and to a method of reducing ozone formation in a process wherein at least a portion of a fluid eventually evaporates.
The fluids and fluid blends of this invention have been selected by the present inventors for their actual or potential low reactivity in the complex photochemical atmospheric reaction with molecular oxygen (O2) and nitrogen oxides (NOx) to create ozone.
The present invention provides a means to reduce ozone formation by photochemical atmospheric reactions from a fluid solvent composition which is intended at application conditions to at least partially evaporate into the atmosphere. By properly selecting low reactive components for a fluid solvent compostion, ozone formation can be reduced.
For the purposes of the present invention three groups of reduced ozone reactivity fluids and their uses are described and claimed: (a) Low Polluting Potential Fluid (LPPF), (b) Very Low Polluting Potential Fluid (VLPPF), and (c) Negligibly Polluting Potential Fluid (NPPF), according to the Absolute MIR numbers as follows:
Where a composition is a blend of fluids, a weight average MIR (WAMIR) can be calculated as
WAMIR=xcexa3Wi*MIRi
Where Wi is a weight fraction of solvent fluid component i and MIRi is the absolute MIR value of solvent fluid component i. For the purposes of the present invention, WAMIR will be the preferred method of measuring xe2x80x9cozone formation potentialxe2x80x9d or OFP.
It is preferred that the fluids and fluid blends also provide at least one other desirable performance property such as high flash point, low particulate formation, suitable evaporation rates, suitable solvency, low toxicity, high thermal stability, and chemical inertness with respect to non-ozone producing reactions, particularly with respect to acids which may be present in coating formulations.
In a particularly preferred embodiment, the fluids are used in a blend with known industrial solvents or other fluids which present an environmental problem with respect to MIR or lack one or more of the aforementioned desirable performance properties, so that the new fluid blends will have lower MIR than they would without the substituted low ozone formation reactivity fluid or have at least one of the aforementioned other desirable performance properties.
The present invention is also directed to a method of reducing ozone formation from atmospheric photochemical reactions in an application wherein a fluid eventually evaporates, at least partially, into the atmosphere, comprising replacing at least a portion of a fluid having a relatively higher MIR with a fluid having a relatively lower MIR. In the case where a blend results, it is preferred that the weighted average MIR of the blend be similar to or less than the MIR of a Low Polluting Potential Fluid, and most preferably similar to the MIR of a Negligibly Polluting Potential Fluid.
A fluid or fluid blend according to the present invention may be used in any process, e.g., any process using a fluid as a carrier, diluent, dispersant, solvent, and the like, on any scale, e.g., pilot plant scale, or industrial scale. It is preferred that the process be a stationary industrial process and it is preferred that the process is a non-combustion process. The present invention offers its greatest benefit from the standpoint of safety and health in large-scale industrial or commercial processes, particularly industrial coating processes or in formulations used in large quantities overall, albeit on a small scale for each individual use, e.g., by a consumer, such as in household paints, cosmetics, and the like. The ordinary artisan can readily differentiate between what is an industrial scale, pilot plant scale, and laboratory scale processes.
Accordingly, it is an object of the present invention to identify liquid organic compounds not heretofore identified as low reactivity solvent fluids and have not been used on a large scale commercial basis to reduce ozone formation.
It is another object of the present invention to provide a method of selecting fluids and/or fluid blends for applications which release fluids into the air and wherein there is a need to reduce ozone formation due to low atmospheric or ground-based (tropospheric) photochemical reactivity, in order to replace conventional solvents and/or solvent blends currently used in various compositions or processes.
It is another object of the present invention to provide a method of optimizing compositions comprising an evaporative fluid by selecting a fluid and/or fluid blend providing a reduced MIR as well as at least one additional performance attribute selected from high flash point, low particulate formation, suitable evaporation rates, suitable solvency, low toxicity, high thermal and chemical stability.
Still another object of the present invention includes the selection of fluids and/or fluid blends providing low reactivity in ozone formation having compatibility with a wide range of organic compounds of different polarity and molecular weights to make the fluids and/or fluid blends suitable for a wide range of compositions.
It is yet another object of the present invention to provide a method of reducing ozone formation caused by the release into the troposphere of a fluid or fluid blend in a process utilizing the fluid or fluid blend, comprising replacing at least a portion of the fluid with another fluid having a lower MIR.
A further object is to provide a method of reducing ground-based ozone formation due to fluid evaporation without resorting to expensive control equipment to capture all fluid emission into the environment.
Another object is to provide solvents that reduce ground base ozone formation without the use of halogenated solvents and their associated toxicity, incineration, and waste disposal issues.
These and other objects, features, and advantages will become apparent as reference is made below to a detailed description, preferred embodiments, and specific examples of the present invention.
The present invention is directed to An industrial formulation-fluid system comprising one or more organic volatile formulation-fluids including a fluid F being substantially free from unsaturated carbon-carbon bonds or aromatic groups. Fluid F is preferably selected from the group consisting of: carbonates, acetates, dioxalanes, pivalates, isobutyrates, propionates, pentanoates, hexanoates, nonanoates, nitriles and mixtures of any two or more thereof, wherein fluid F is present in an amount such that the formulation-fluid system exhibits a reduction in ozone formation in an amount of at least 10%, preferably at least 25%, and more preferably at least 50% less than that of the formulation-fluid system without fluid F. Moreover, fluid F has an ozone formation potential (OFP) (in accordance with the Absolute MIR scale in units of g. ozone/g. fluid F) of xe2x89xa61.5.
Fluid F preferably comprises an oxygen-containing functional group or a nitrogen-containing functional group. The oxygen-containing functional group is preferably selected from the groups consisting of: xe2x80x94ROCOORxe2x80x2, xe2x80x94COOR and xe2x80x94RORxe2x80x2, and the nitrogen-containing functional group is xe2x80x94RCN, wherein R and Rxe2x80x2 are both selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, isobutyl, tertiary butyl, neopentyl and 2,4,4-trimethylpentyl. Moreover, hydrocarbyl moieties R and Rxe2x80x2 have, collectively, a ratio of methyl hydrogen to non-methyl hydrogen of either (1) greater than 1, (2) greater than 5, or (3) greater than or equal to 9.
Fluid F preferably comprises a compound selected from the group consisting of: dimethyl carbonate, methyl pivalate, methyl ethyl carbonate; methyl isopropyl carbonate; methyl neopentyl carbonate; methyl tertiary butyl carbonate; diisopropyl carbonate; neopentyl acetate; ethylene glycol diacetate; 1,2-propylene glycol diacetate; 1,3-propylene glycol diacetate; 1,2-butylene glycol diacetate; 1,3-butylene glycol diacetate; 2,3-butylene glycol diacetate; neopentyl glycol diacetate; methyl propionate, ethyl propionate, isopropyl propionate and n-propyl propionate, 2,2-dimethyl dioxolane; 2,2,4-trimethyl dioxolane; 2,2,4,5-tetramethyl dioxolane; ethyl pivalate; isopropyl pivalate; tertiary butyl pivalate; neopentyl pivalate; pivalonitrile; ethylene glycol monopivalate; 1,2-propylene glycol monopivalate; 1,2-butylene glycol monopivalate; 2,3-butylene glycol monopivalate; ethylene glycol pivalate acetate; ethylene glycol dipivalate; 1,2-propylene glycol pivalate acetate; 1,2-butylene glycol pivalate acetate; 1,3-butylene glycol pivalate acetate; 2,3-butylene glycol pivalate acetate; 1,2-propylene glycol dipivalate; neopentyl glycol monopivalate; neopentyl glycol pivalate acetate; isopropyl isobutyrate; neopentyl isobutyrate; methyl 2,2,4,4-tetramethyl pentanoate (methyl neononanoate), isopropyl neononanoate; 2,2,4,4-tetramethyl pentanonitrile; neopentyl glycol monoisobutyrate; methyl 3,5,5-trimethylhexanoate, and mixtures of any two or more thereof.
The present invention also includes an industrial formulation-fluid system comprising one or more organic volatile formulation-fluids including a fluid F being substantially free from unsaturated carbon-carbon bonds or aromatic groups, wherein fluid F is selected from the group consisting of: carbonates, acetates, dioxalanes, pivalates, isobutyrates, propionates, pentanoates, hexanoates, nonanoates, nitriles and mixtures of any two or more thereof, and wherein fluid F is present in an amount such that the formulation-fluid system has an ozone formation potential (OFP) that is at least 10% less than that of the formulation-fluid system without fluid F.
The present invention also pertains to a non-combustion process utilizing a process fluid or composition comprising a first fluid wherein at least some of the first fluid evaporates into the atmosphere, wherein the process involves replacing at least a portion of the first fluid with a second fluid, i.e., fluid F, wherein fluid F has an ozone formation potential (OFP) (in accordance with the Absolute MIR scale in units of g. ozone/g. fluid F) of xe2x89xa61.5 and is present in an amount such that the process fluid has an OFP that is at least 10% less than that of the process fluid without fluid F, thereby decreasing ozone formation from atmospheric photochemical reactions resulting from performance of the process.
The process fluid according to the present invention preferably acts as a solvent, carrier, diluent, surface tension modifier, or any combination thereof, in the process. Moreover, the process fluid does not contain a halocarbon.
The present invention also pertains to a composition comprising: (1) a first fluid wherein at least some of the first fluid evaporates into the atmosphere; and (2) a second fluid comprising an oxygen-containing functional group or a nitrogen-containing functional group and being substantially free from unsaturated carbon-carbon bonds or aromatic groups. The second fluid being selected from the group consisting of carbonates, acetates, dioxalanes, pivalates, isobutyrates, pentanoates, hexanoates, nonanoates, nitriles and mixtures of any two or more thereof, wherein the second fluid has an ozone formation potential (OFP) (in accordance with the Absolute MIR scale in units of g. ozone/g. fluid F) of xe2x89xa61.5 and is present in an amount such that the composition has an OFP of, or reduces ozone formation by, at least 10% less than that of the composition without the second fluid.
The fluids used in accordance with this invention have been selected for their low or reduced ozone formation potential (as reflected in their low or reduced MIR). The ozone formation potential of a composition or fluid solvent may be determined by any scientifically recognized or peer reviewed method including but not limited to, the MIR scale, the KOH scale, smog chamber studies, and modeling studies such as those performed by Dr. William P. L. Carter. Most references in the description of the present invention will be to the Absolute MIR scale measured in grams ozone produced/gram of fluid solvent. By xe2x80x9clow MIRxe2x80x9d is meant that the fluids have an MIR similar to or less than 1.5 gram of ozone per gram of the solvent fluid. By xe2x80x9creduced MIRxe2x80x9d is meant that, in a process according to the present invention, a first fluid is replaced, in whole or in part, by a second fluid, the second fluid having an MIR lower than the first fluid. One of ordinary skill in the art can determine ozone reactivity of a material according to methods in numerous literature sources and tabulated data published in the open literature. It is mentioned that the terms xe2x80x9creplacexe2x80x9d, xe2x80x9creplacementxe2x80x9d, xe2x80x9creplacingxe2x80x9d and the like used herein are not to be taken as implying only the act of substituting a second fluid (having acceptable MIR as described herein) in a formulation for a first fluid that may have been previously used in that and similar formulation(s), with such first fluid has undesirable MIR as described herein. Rather, the terms are intended to include the formulations themselves comprising a mixture of the first and second fluids, or one or more such second fluid(s) without any of said first fluid(s), as the fluid system of the formulation. In the case where no such first fluid(s) are present, the concept of xe2x80x9creplacementxe2x80x9d is intended to refer to corresponding formulations that have only such first fluid(s) present instead of such second fluid(s) and therefore have a lower OFP.
The MIR is preferably determined by smog chamber studies, modeling studies, or a combination thereof, but is more preferably determined by xe2x80x9cincremental reactivityxe2x80x9d, and still more preferably by the Absolute MIR, as discussed above.
The MIR of a fluid used in this invention is preferably less than or equal to 1.5 gram of ozone per gram of solvent fluid, more preferably less than or equal to 1.0 gram of ozone per gram of solvent fluid, and most preferably less than or equal to 0.5 gram of ozone per gram of solvent fluid, but the benefits of the present invention are realized if ozone formation is reduced by replacing a first fluid with a second fluid, in whole or in part, wherein the MIR of the second fluid is reduced from that of the first fluid, even if the second fluid has an MIR greater than 1.5 gram of ozone per gram of solvent fluid.
Therefore, it is preferred that the fluid according to the present invention have an MIR less than or equal to 1.50 and more preferably less than or equal to 1.00, still more preferably less than or equal to 0.50. In an even more preferred embodiment, the reactivity in ozone formation is preferably equal to or less than that of acetone and even more preferably equal to or less than that of ethane, by whatever scale or method is used, but most preferably by the MIR scale. Thus, in a more preferred embodiment, the fluid used in a composition according to the present invention will have an MIR less than or equal to 0.50, even more preferably less than or equal to 0.35.
Specifically preferred fluids according to the present invention include:
dialkyl carbonates, such as dimethyl carbonate (DMC), methyl ethyl carbonate, methyl isopropyl carbonate, methyl sec-butyl carbonate, methyl t-butyl carbonate, methyl neopentyl carbonate, and diisopropyl carbonate;
alkyl acetates, such as neopentyl acetate, ethylene glycol diacetate, 1,2-propylene glycol diacetate, 1,3-propylene glycol diacetate, 1,2-butylene glycol diacetate, 1,3-butylene glycol diacetate, 2,3-butylene glycol diacetate, neopentyl glycol diacetate;
dioxolanes such as 2,2-dimethyl dioxolane, 2,2,4-trimethyl dioxolane, 2,2,4,5-tetra methyl dioxolane;
pivalates such as methyl pivalate (methyl 1,1,1-trimethyl acetate), ethyl pivalate, isopropyl pivalate, t-butyl pivalate (TBP), neopentyl pivalate (NPP), 1,2-propylene glycol bis-pivalate (PGBP), ethylene glycol bis-pivalate, ethylene glycol monopivalate, 1,2-butylene glycol mono-pivalate (1,2-BGMP), 2,3-butylene glycol monopivalate (2,3-BGMP), 1,2-butylene glycol pivalate acetate (1,2-BGPA), 1,2-butylene glycol pivalate acetate (1,2-BGPA), 2,3-butylene glycol pivalate acetate (2,3-BGPA), ethylene glycol pivalate acetate, 1,2 propylene glycol monopivalate, neopentyl glycol mono pivalate, and 1,2-propylene glycol pivalate acetate;
isobutyrate compounds such as isopropyl isobutyrate, neopentyl isobutyrate, and neopentyl glycol mono isobutyrate;
propionate compounds such as methyl propionate, ethyl propionate, isopropyl propionate and n-propyl propionate; and
2,2,4,4-tetramethyl pentanonitrile (TMPN); isopropyl neononanoate; pivalonitrile; methyl 2,2,4,4-tetramethyl pentanoate (methyl neononanoate) and methyl 3,5,5 trimethyl hexanoate. Other preferred fluids are oxygenated (oxygen containing) organic compounds substantially free of moieties containing unsaturated carbon-carbon bonds or aromatic groups.
In the case of a blend, the weighted average MIR of the fluids in a composition according to the present invention will also have the perferred, more preferred, and most preferred MIR levels as discussed above.
In another preferred embodiment, wherein the blend results from replacing part of a first fluid with a second fluid and thereby reducing the weight average MIR, it is preferred that the weight average MIR be reduced 10%, more preferably 25%, still more preferably 50%, from the MIR calculated prior to the fluid replacement.
In yet another preferred embodiment, the Low Polluting Potential Fluids (LPPF), Very Low Polluting Potential Fluids (VLPPF), and Negligibly Polluting Potential Fluids (NPPF), as described herein will provide at least one other desirable performance property such as high flash point low particulate formation, suitable evaporation rates, suitable solvency, low toxicity, high thermal stability, and chemical inertness. Of course, it is more preferable that the fluid or blends have two or more of these performance attributes, and so on, so that the most preferred fluid or fluid blend has all of these performance attributes.
In the case of a process of reducing ozone formation, wherein a fluid according to the present invention replaces a fluid, at least in part, having a higher MIR, described in more detail below, it is preferred that this fluid replacement process, in addition to reducing ozone formation does not negatively impact any other desirable performance attributes of the composition as described above.
The flash point of a fluid according to the present invention is preferably at least xe2x88x926.1xc2x0 C. or higher, more preferably greater than +6.0xc2x0 C., even more preferably greater than 15xc2x0 C., still more preferably greater than 25xc2x0 C., yet even more preferably greater than 37.8xc2x0 C., and most preferably greater than 60xc2x0 C. One of ordinary skill in the art can readily determine the flash point of a fluid or blend (e.g., ASTM D92-78).
In the case of a blend, the flash point of the blend may be the flash point of the more volatile component, in the instance where the flash points of the individual components differ markedly or where the more volatile component is the predominant component. The flash point of the blend may be in between the flash points of the individual components. As used herein, the term xe2x80x9cflash pointxe2x80x9d will refer to the flash point experimentally determined for a single fluid or a blend, as applicable.
The fluid or blend thereof, according to the present invention, should preferably not contribute measurably to particulate formation of particulates having a size diameter below 2.5 xcexcmxe2x80x94referred to as 2.5 PM hereinxe2x80x94in the atmosphere. In a preferred embodiment of a process of reducing ozone formation, the fluid selected to replace a previously-used solvent will be one that also reduces particulate matter to less than or equal to 65 xcexcg/m3, and more preferably less than or equal to 50 xcexcg/m3, when measured over a 24-hour period, preferably spatially averaged over all monitors in a given geographic area.
The evaporation rate should be suitable for the intended purpose. In many if not most applications, the fluid according to the present invention will be used to replace, at least in part, a fluid which is environmentally disadvantaged, meaning it has a reactivity in ozone formation greater than 1.5 in Absolute MIR units. The fluid selected preferably will have a similar evaporation rate to the disadvantaged fluid being replaced, particularly in the case where a fluid blend is used and an acceptable evaporation profile is desired. It is convenient for the fluid selected to have an evaporation rate less than 12 times the evaporation rate of n-butyl acetate. Evaporation rates may also be given relative to n-butyl acetate at 1.0 (ASTM D3539-87). Ranges of evaporation rates important for different applications are 5-3, 3-2, 2-1, 1.0-0.3, 0.3-0.1, and  less than 0.1, relative to n-butyl acetate at 1.0. The present invention is related to fluids and fluid blends that at least partially evaporate into the atmosphere during or after their application. The use of fluids of the present invention is preferred when  greater than 25% of the fluid is evaporated, more preferably when  greater than 50% of the fluid is evaporated, more preferably when  greater than 80% of the fluid is evaporated, more preferably when  greater than 95% of the fluid is evaporated, and most preferably when  greater than 99% of the fluid is evaporated. In a preferred embodiment of the present invention wherein, in a method of reducing ozone formation, a fluid according to the present invention replaces, at least in part, another fluid not according to the present invention, the fluid replaced has an evaporative rate ranging from that of MEK (methyl ethyl ketone) to less than that of n-butyl acetate.
The fluid or fluid blend according to the present invention may act in the traditional manner of a solvent by dissolving completely the intended solute or it may act to disperse the solute, or it may act otherwise as a fluid defined above. It is important that the solvency of the fluid be adequate for the intended purpose. In addition to the required solvency, the formulated product must be of a viscosity to enable facile application. Thus, the fluid or fluid blend must have the appropriate viscosities along with other performance attributes. One of ordinary skill in the art, in possession of the present disclosure, can determine appropriate solvent properties, including viscosity.
Toxicity relates to the adverse effect that chemicals have on living organisms. One way to measure the toxic effects of a chemical is to measure the dose-effect relationship; the dose is usually measured in mg of chemical per kg of body mass. This is typically done experimentally by administering the chemical to mice or rats at several doses in the lethal range and plotting the logarithm of the dose versus the percentage of the population killed by the chemical. The dose lethal to 50% of the test population is called the median lethal dose (LD50) and is typically used as a guide for the toxicity of a chemical. See, for instance, Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, Vol. 24, pp. 456-490. Currently an LD50 of  greater than 500 mg/kg qualifies as xe2x80x9cnot classifiedxe2x80x9d for oral toxicity under OSHA rules. EU (European Union) uses a cutoff of  greater than 2,000 mg/kg. It is preferred that the fluid or fluid blend according to the present invention have an oral rat LD50 of  greater than 500 mg/kg, more preferably  greater than 1000 mg/kg, still more preferably  greater than 2,000 mg/kg, even more preferably  greater than 3,000 mg/kg, and most preferably  greater than 5,000 mg/kg. Likewise, the fluid or blend should also cause no toxicity problems by dermal or inhalation routes and should also not be an eye or skin irritant, as measured by OSHA or European Union (EU) standards.
As described above, the present invention is related to fluid solvents and fluid solvent blends which produce reduced ozone formation due to atmospheric photochemical reactions and which avoid the deficiencies associated with halogenated organic compounds, particularly toxicity, ozone depletion, incineration by-products and waste disposal problems. In this aspect, the volatile components of the preferred fluid solvents and fluid solvent blends preferably do not have more than 2.0 wt. % of halogen and more preferably less than 0.5 wt. %, and most preferably less than 0.1 wt. %.
The fluid according to the present invention should be thermally stable so that it does not break down. For instance, the material should not break down into reactive species. In a preferred embodiment, the fluid is more thermally stable than t-butyl acetate.
Inertness, as used herein, refers to the lack of a tendency to undergo decomposition with other materials in the fluid system. It may include, for example, inertness towards acids or bases, but particularly to acid catalysts, which are typically present in coating compositions.
It is preferred that the fluid being replaced have an MIR greater than that of acetone. In another embodiment, the incremental reactivity, based on the MIR scale, of the fluid being replaced is preferably  greater than 0.50, still more preferably  greater than 0.1.00, and most preferably  greater than 1.50.
In another embodiment, it is critical that in a process of reducing tropospheric ozone formation according to the present invention, the fluid replaced have a greater MIR than the fluid added, that is, the fluid according to the present invention. Of course it is to be recognized that only a portion of the higher MIR fluid need be replaced, thus obtaining a blend, in order to achieve the ozone formation reduction.
However, in another embodiment of the present invention, the fluid being replaced may have an acceptable MIR, but be unacceptable with respect to one or more of the aforementioned performance attributes of flash point or flammability, particulate formation, evaporation rate, solvency, toxicity, thermal stability, or inertness. Examples of a given blend of DMC and MEK will be provided wherein the appropriate addition of DMC (or xe2x80x9creplacementxe2x80x9d of acetone) provided for an improvement in at least one of these attributes.
Examples of fluids which are replaced by fluids according to the present invention include aromatic and aliphatic hydrocarbon fluids such as: branched C6-C9 alkanes, straight chain alkanes, cycloaliphatic C6-C10 hydrocarbons, natural hydrocarbons (alpha or beta pinenes, or turpentines, etc.), ethanol, propanol and higher nontertiary alcohols, C3 and higher ethers, ether alcohols, ether alcohol acetates, ethyl ethoxy propionate, C5 and higher ketones, cyclic ketones, etc., C7+ aromatic hydrocarbons; halocarbons, particularly chlorinated and brominated hydrocarbons; and ethers such as cyclic ethers such as tetrahydrofuran (THF),. Examples of other common industrial solvents which may be replaced by fluids according to the present invention are those listed in Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, Vol. 22, p. 536-548.
Some particularly preferred replacements, i.e., a fluid according to the present invention for a currently used industrial solvent, include: in any application, but particularly coatings applications, DMC or methyl pivalate for toluene, xylene, or t-butyl acetate; methyl isopropyl carbonate (MIPC) for xylene or methyl isobutyl ketone (MIBK); and diisopropyl carbonate (DIPC) for methyl amyl ketone (MAK), propylene glycol monomethyl ether acetate (PMAc), or ethyl ethoxy propionate (EEP); in any application, but particularly consumer product applications DMC, MIPC, or DIPC for hydrocarbons; in any application but particularly agricultural applications, DIPC for aromatic fluids; in any application but particularly cleaning applications, DIPC or methyl sec-butyl carbonate (MSBC) for chlorinated solvents; in any application, but particularly inks, substitute DMC or methyl pivalate for MEK and light acetates.
The fluids and blends according to the present invention may be used in any process using a fluid, and particularly those process wherein at least a portion of the fluid evaporates and even more particularly wherein at least a portion evaporates into the atmosphere. Preferred processes are those utilizing the fluid as one or more of a carrier, diluent, dispersant, solvent, and the like, include processes wherein the fluid functions as an inert reaction medium in which other compounds react; as a heat-transfer fluid removing heat of reaction; to improve workability of a manufacturing process; as a viscosity reducer to thin coatings to application viscosity; as an extraction fluid to separate one material from another by selective dissolution; as a tackifier or to improve adhesion to a substrate for better bonding; as a dissolving medium to prepare solutions of polymers, resins, and other substances; to suspend or disperse pigments and other particulates; and the like.
It is preferred that the process be a stationary process and also preferred that the process be a non-combustion process. It is particularly beneficial if the fluid according to the present invention be used to replace at least a portion of a traditional industrial solvent in a process using a large amount of fluid, e.g., a process using 1000 lb/year (500 kg/year), even more preferably 5 tons/year (5000 kg/yr), still more preferably 50 tons/year (50,000 kg/yr), and most preferably one million lbs/year (500,000 kg/yr). In a preferred embodiment, the process wherein the aforementioned fluid replacement occurs is on the scale of at least pilot plant-scale or greater.
It is also preferred that the process in which a fluid or blend according to the present invention is used or in which at least one fluid according to the present invention replaces, at least partially, a fluid having a higher MIR, be a process in which the fluid is intended to evaporate, such as in a coating process. In such a process were the fluid is intended to evaporate, it is preferred that at least 10% of the fluid or fluids evaporate, more preferably 20% of the fluids, and so on, so that it is most preferable if  greater than 99% of the fluid or fluids present in the coating evaporate.
Furthermore, one of the greatest environmental benefits of replacing a currently-used industrial solvent with a solvent according to the present invention will be realized if performed in a geographic area where monitoring for ozone and particulate matter formation occurs, and more particularly in geographic areas defined by a city and its contiguous area populated by at least 500,000 persons, and wherein the replacement of at least a portion of the currently-used industrial solvent with a fluid according to the present invention causes at least one of:
(i) a reduction in the ozone formation, as measured by either monitoring devices or by a calculation of the reduction using the MIR of the industrial solvent replaced and the fluid added according to the present formation; or
(ii) a reduction in particulate formation of particles having a diameter less than 2.5 xcexcm (2.5 PM), preferably measured as a 24 hour standard, more preferably wherein that reduction is from greater than 65 xcexcg/m3 to less than that amount in a 24 hour period, still more preferably from greater than 65 xcexcg/m3 to less than or equal to 50 xcexcg/m3 in a 24 hour period;
and more preferably both (i) and (ii).
In another embodiment, there is a method of selecting a fluid for use in a process wherein at least a portion of the fluid eventually evaporates into the atmosphere, comprising selecting as the fluid a blend of:
(a) at least one fluid A having a low MIR, preferably similar to or less than or equal to 1.50, more preferably less than or equal to 1.00, yet still more preferably wherein the MIR is less than or equal to 0.50 and still even more preferably less than or equal to 0.35; and
(b) at least one fluid B characterized by having at least one unsuitable attribute selected from: (i) high MIR, preferably measured by the MIR scale, e.g., having an MIR greater than 0.50, more preferably  greater than 1.00, and yet even more preferably  greater than 1.50; (ii) low flash point, preferably less than or equal to 37.8xc2x0 C., more preferably less than or equal to 250xc2x0 C., even more preferably less than or equal to 15xc2x0 C., yet even more preferably less than or equal to 6.0xc2x0 C., and most preferably less than xe2x88x926.1xc2x0 C.; (iii) formation of 2.5 PM particulates (e.g., wherein said process, using fluid B, produces 2.5 PM greater than 65 micrograms per cubic meter or greater, as measured in a 24-hour period); (iv) toxicity, preferably those having an oral rat LD50 less than or equal to 1,000 mg/kg, and most preferably less than or equal to 500 mg/kg; (vi) thermal stability, preferably having a thermal stability equal to or less than (more unstable) than t-butyl acetate; and (vii) inertness in the fluid or fluid blend, particularly with respect to any acids or bases present in the fluid or blend.
Preferred examples of fluid A include:
dialkyl carbonates, such as dimethyl carbonate (DMC), methyl ethyl carbonate, methyl isopropyl carbonate, methyl sec-butyl carbonate, methyl t-butyl carbonate, methyl neopentyl carbonate, and diisopropyl carbonate;
alkyl acetates, such as neopentyl acetate, ethylene glycol diacetate, 1,2-propylene glycol diacetate, 1,3-propylene glycol diacetate, 1,2-butylene glycol diacetate, 1,3-butylene glycol diacetate, 2,3-butylene glycol diacetate, neopentyl glycol diacetate;
dioxolanes such as 2,2-dimethyl dioxolane, 2,2,4-trimethyl dioxolane, 2,2,4,5-tetra methyl dioxolane;
pivalates (trimethyl acetates) such as methyl pivalate (MP), isopropyl pivalate, t-butyl pivalate (TBP), neopentyl pivalate (NPP), 1,2-propylene glycol bis-pivalate (PGBP), ethylene glycol bis-pivalate, ethylene glycol monopivalate, 1,2-butylene glycol mono-pivalate (1,2-BGMP), 2,3-butylene glycol monopivalate (2,3-BGMP), 1,2-butylene glycol pivalate acetate (1,2-BGPA), 1,2-butylene glycol pivalate acetate (1,2-BGPA), 2,3-butylene glycol pivalate acetate (2,3-BGPA), ethylene glycol pivalate acetate, 1,2 propylene glycol monopivalate, neopentyl glycol mono pivalate, and 1,2-propylene glycol pivalate acetate;
isobutyrate compounds such as isopropyl isobutyrate, neopentyl isobutyrate, and neopentyl glycol mono isobutyrate;
propionate compounds such as methyl propionate, ethyl propionate, isopropyl propionate and n-propyl propionate; and
2,2,4,4-tetramethyl pentanonitrile (TMPN); isopropyl neononanoate; pivalonitrile; methyl 2,2,4,4-tetramethyl pentanoate (methyl neononanoate); and methyl 3,5,5 trimethyl hexanoate.
Preferred examples of fluid B include aromatic and aliphatic hydrocarbon fluids such as toluene and xylenes; alcohols such as ethanol, n-butyl alcohol, n-propyl alcohol, and sec-butanol; esters such as ethyl ethoxy propionate propylene glycol methyl ether acetate; ketones such as methyl ethyl ketone (MEK), C5-C10 linear ketones, cyclic ketones; halocarbons, particularly chlorinated and brominated hydrocarbons; cyclic ethers such as THF, and non-cyclic ethers such as methyl tert-butyl ether (MTBE).
The present invention also concerns mixtures or blends of at least one fluid according to the present invention and fluids which are known to have acceptable low OFP, e.g., acetone (MIR=0.48), methyl acetate (MIR=0.12), tert-butyl acetate (MIR=0.21), tertiary butanol (MIR=0.40), dimethyl succinate (MIR=0.20), dimethyl glutarate (MIR=0.40), and propylene carbonate (MIR=0.43). Such blends can have some important advantages, for example, blends of DMC and MEK, or DMC and methyl acetate, as previously mentioned. These blends are also considered to be part of the present invention. In combination with fluids having an MIR higher than 0.50, the fluids still can provide significant reduction in ozone formation for blended fluid compositions with other important properties for the particular application. Therefore, fluid compositions with low or reduced OFP comprising solvents selected from the list above are important goals of the present invention, even if their weighted OFP is above 0.50 in the MIR scale.
The fluids listed above are recommended to be used in solvent compositions intended for release into air and are required to provide low reactivity in ozone formation. The solvents selected according to the present invention can be used in blends with each other as well as in blends with other solvents (e.g., solvents B, above), different from the solvents of the present invention. When all solvents included in the blend have MIR reactivity xcx9c0.50 or less, the solvent blends also will have low atmospheric photochemical reactivity with MIR of about 0.50 and less.
The present inventors have found that many solvent blends can have an MIR in the range of ethane or acetone, even though one component may exceed that range, and therefore in terms of reactivity toward ozone formation behave as exempt solvents. The range of reactivities in exempt solvents allows a selection of fluids with extremely low reactivity, with MIR number in range of xe2x89xa60.35 and more suitably xe2x89xa60.24. These fluids can be blended not only with fluids with reactivity based on MIR of xcx9c0.50 or less but, with appropriately selected fluids with MIR numbers  greater than 0.50 and at certain ratios still form fluid compositions with weighted reactivity about 0.50 or less. These blends can significantly expand the range of properties of solvent compositions and provide formulators with necessary flexibility for different applications. The selection of fluids with MIRs  greater than 0.50 can be relatively wide, however, to achieve significant reduction in weighted reactivity to xcx9c0.50 or less, it is recommended to choose solvent with MIR  less than 1.5, suitably  less than 1.2, and more suitably  less than 1.0.
The conception of blends demonstrating MIR of about 0.50 or less can be applied to other solvents with known extremely low reactivities. For example, methyl acetate has an MIR 0.12 but flash point xcx9cxe2x88x9212xc2x0 C. Thus, methyl acetate can be blended with butyl acetate (MIR=1.00 and flash point 27xc2x0 C.) in weight ratio of 57:43 forming a blend with MIR=0.50, providing reactivity similar to exempt solvents. This blend would have a better flash point and lower evaporation rate, making it useful for many applications which methyl acetate could not satisfy due to very low flash point. Butyl acetate which is not an exempt solvent, would become part of a mixture which by its weighted reactivity would behave similar to exempt solvent and, therefore, constitute preferred solvent composition.
This special case of blends comprising at least one solvent with MIR reactivity  less than 0.50 and at least one solvent with MIR  greater than 0.50 which have their weighted reactivity about 0.50 or less is one very important part of the present invention. Among known solvents with extremely low MIR, suitable components for the preferred blended solvents are methyl acetate (MIR=0.12), t-butyl acetate (MIR=0.21), dimethyl succinate (MIR=0.20) and methyl siloxanes including cyclomethylsiloxanes. Blends of these solvents with other solvents with MIR  greater than 0.50 resulting in weighted MIR of about 0.50 or less for the blend are preferred solvents according to the present invention.
However, some of the most interesting blends are the blends of at least one solvent with MIR reactivity  less than 0.50 and with at least one with MIR reactivity  greater than 0.50, which can be generated with the solvents from the list of the present invention.
The present invention offers fluids and fluid blends for use in a variety of industrial applications such as paints and other coatings, adhesives, sealants, agricultural chemicals, cleaning solution, consumer products such as cosmetics, pharmaceuticals, drilling muds, extraction, reaction diluents, inks, metalworking fluids, etc.
Among the most preferred fluids according to the present invention are dimethyl carbonate and methyl pivalate. Table 1 demonstrates the extremely low relative reactivitiesxe2x80x94significantly lower than both acetone and ethanexe2x80x94of dimethyl carbonate and methyl pivalate. This data shows that these two compounds satisfy the EPA requirements for exempt solvents in accordance with current VOC regulations and demonstrating extremely low reactivity for the possible future reactivity based rules. Additionally, DMC is shown to be one of the lowest reactivity compounds among all currently known oxygenated compounds.
Table 2a shows the conversion of a portion of the data in Table 1 into Absolute Maximum Incremental Reactivities for the dimethyl carbonate and methyl pivalate. As seen from Table 2, Absolute Ozone Formation for different levels of NOx in ROG is highest for highest level of NOx scenario (MIR) and lowest for lowest level of NOx scenario (EBIR). As a result, Absolute Reactivity in atmospheric photochemical ozone formation for tested compounds is highest for MIR scenario and lowest for EBIR scenario. This data demonstrates the outstanding value as Low Polluting Potential Fluids (LPPF), Very Low Polluting Potential Fluid (VLPPF), and Negligibly Polluting Potential Fluid (NPPF). Additionally Table 2b shows both compounds as having acceptable flash points, boiling temperatures, evaporation rates, low toxicity, good solvency and overall outstanding performance as versatile environmentally preferred exempt, extremely low ozone formation fluids (solvents) for a very wide range of applications.
Likewise, dimethyl carbonate (DMC) is highly preferable and can be blended with another organic solvent, even one having an Absolute MIR greater than 0.50 to form a solvent system that would still have an Absolute MIR of less than 0.50. DMC blended with another organic solvent would also exhibit other desirable environmental properties because DMC has a relatively high flash point and low toxicity. Again, heretofore unrecognized as a low OFP fluid, the Relative MIR of DMC is calculated to be 0.02, using the SAPRC97 model.
The compounds presented in Tables 3-5 show calculated Absolute MIR reactivities for compounds useful as Low Polluting Potential Fluids (LPPF), Very Low Polluting Potential Fluids (VLPPF), and Negligibly Polluting Potential Fluids (NPPF) or as part of a fluid solvent blend. These fluids provide favorable MIR reactivities, a very wide range of evaporation rates, and a wide range of solvency and compatability with other solvents, polymers, pigments, catalysts, additives, etc., necessary for actual applications. All the compounds listed in the present invention, especially in Tables 2a-5, are very useful as substitute conventional solvents having an Absolute MIR between 1.5 and 3.0 and especially in solvents having high reactivity Absolute MIR greater than 3.0 in atmospheric photochemical ozone formation.
It should be noted that calculated values for the Absolute and the Relative MIR reactivity for DMC and MP were very close to the actual laboratory determined values.
The most preferred use of the fluids according to the present invention is with any process wherein the reduction of ozone formation is desired, and more particularly in consumer products, and coatings such as auto refinishing, architectural and industrial coatings and paints.
Paints and coatings comprise the largest single category of traditional solvent consumption, accounting for nearly half the solvents used. Fluids serve multiple functions in paints and coatings, including solubility, wetting, viscosity reduction, adhesion promotion, and gloss enhancement. Fluids dissolve the resins, dyes and pigments used in the coating formulations. Also, prior to application, it is common practice to add solvent thinner to attain the desired viscosity for the particular application. Solvents begin to evaporate as soon as the coating materials are applied. As the solvent evaporates, film formation occurs and a continuous, compact film develops. Single solvents are sometimes used in coatings formulations, but most formulations are blends of several solvents. In many coatings applications, the solvent system includes a slow-evaporating active solvent that remains in the film for an extended period to enhance the film""s gloss and smoothness. Because of evaporation and the large amounts of solvents used in coatings, there is a significant amount of VOC emissions into the atmosphere.
Resins which may be incorporated into compositions comprising fluids according to the present invention include acrylic, alkyd, polyester, epoxy, silicone, cellulosic and derivatives thereof (e.g., nitrocellulosic and cellulosic esters), PVC, and isocyanate-based resins. Numerous pigments may also be incorporated into compositions according to the present invention, and it is within the skill of the ordinary artisan to determine proper selection of the resin and pigment, depending on the end use of the coating.
One of the cleaning applications is cold solvent cleaning which is used to degrease metal parts and other objects in many operations. Mineral spirits have been popular in cold cleaning, but are being supplanted by higher flash point hydrocarbon solvents due to emissions and flammability concerns. Efforts to eliminate organic solvents entirely from cleaning compositions have not been successful because aqueous cleaners do not have the performance properties that make organic solvent based cleaners so desirable. This invention allows formulators the option to seek the use of solvents with very low reactivity as environmentally preferred products meeting environmental concerns and customer performance concerns.
A cleaning solution application which uses evaporation to clean is called vapor degreasing. In vapor degreasing, the solvents vaporize and the cold part is suspended in the vapor stream. The solvent condenses on the part, and the liquid dissolves and flushes dirt, grease, and other contaminants off the surface. The part remains in the vapor until it is heated to the vapor temperature. Drying is almost immediate when the part is removed and solvent residues are not a problem. The most common solvent used in vapor degreasing operations has been 1,1,1-trichloroethane. However, since 1,1,1-trichloroethane is being phased out due to ozone depletion in the stratosphere, alternatives are needed. Moreover, chlorine-based solvents have toxicity concerns. Thus, some of the low reactivity, high flash point solvents in this invention can be used in place of 1,1,1-trichloroethane and other halogenated solvents.
An application that is similar to coatings is printing inks. In printing inks, the resin is dissolved in the solvent to produce the ink. Most printing operations use fast evaporating solvents for best production speeds, but the currently used solvents are highly reactive. Some of the previously described fast evaporation, high flash point, low reactivity in ozone formation fluids according to the present invention are suitable for printing inks.
An application that is suitable to the low toxicity, high flash point and low reactivity in ozone formation fluids according to the present invention is agricultural products. Pesticides are frequently applied as emulsifiable concentrates. The active insecticide or herbicide is dissolved in a hydrocarbon solvent which also contains an emulsifier. Hydrocarbon solvent selection is critical for this application. It can seriously impact the efficiency of the formulation. The solvent should have adequate solvency for the pesticide, promote good dispersion when diluted with water, have low toxicity and a flash point high enough to minimize flammability hazards.
Extraction processes, used for separating one substance from another, are commonly employed in the pharmaceutical and food processing industries. Oilseed extraction is a widely used extraction process. Extraction-grade hexane is a common solvent used to extract oil from soybeans, cottonseed, corn, peanuts, and other oil seeds to produce edible oils and meal used for animal feed supplements. Low toxicity, high flash point, low MIR fluids and fluid blends of the present invention can be useful in such industries.
In addition to the above-mentioned applications, other applications that can use high flash point, low toxicity, low reactivity in ozone formation fluids are adhesives, sealants, cosmetics, drilling muds, reaction diluents, metal working fluids, and consumer products, such as pharmaceuticals or cosmetics.